Two simple, rapid and sensitive spectrophotometric methods for the determination of josamycin and ciprofloxacin in their pharmaceutical dosage forms are described. Method (A) is based on the reaction of aldehyde group of josamycin with 2,4-dinitrophenyl hydrazine in methanolic hydrochloric acid to yield a yellow product which absorbs maxima at 411 nm, whereas method (B) depends on the reaction of
ciprofloxacin with 1,2-naphthaquinone-4-sodium sulphonate in alkaline medium to form an orange coloured product measurable at 487 nm. The working conditions of both methods have been optimized and the reactions pathways were postulated. Regression analysis of Beer's law plots showed good correlation in the concentration ranges 10-160 and 5-120 μg/mL for josamycin and ciprofloxacin,
respectively. Detection and quantification limits for both methods are calculated. The methods were successfully applied to the determination of both drugs in bulk drugs and their formulations. Statistical treatment of the experimental results indicates that the accuracy and precision of the methods are analytically acceptable. The validity of the methods was evaluated by parallel determinations by established procedures and by recovery studies.